diff --git a/bl31/bl31.mk b/bl31/bl31.mk
index c0dc2fd..6c9650f 100644
--- a/bl31/bl31.mk
+++ b/bl31/bl31.mk
@@ -37,6 +37,7 @@
 				bl31/aarch64/runtime_exceptions.S		\
 				bl31/aarch64/crash_reporting.S	\
 				common/aarch64/early_exceptions.S		\
+				lib/aarch64/cpu_helpers.S			\
 				lib/locks/bakery/bakery_lock.c			\
 				lib/locks/exclusive/spinlock.S			\
 				services/std_svc/std_svc_setup.c		\